Basic help, Illustrator to photoshop (size problem)

Hi all,
I have experince in photoshop but I am new to illustrator, I have a illustrator file .ai and the size of file is 200x200 px and I want the size to 500x500 px. and use the file in photoshop, Now I don't know that how to increase the file size (diamentions) of an illustrator file? Is it an exporting option or somewhere else to increse the file size. Please help, Thanks in advance

You could set the size to 500x500 in the Photoshop import dialogue, during import.

Or, Set the Illustrator file's document size to 500x500 (File/Document Setup) than resize the art to fit.
You may need to go into Illustrator's preferences and enable 'Scale Strokes and Weights', prior to scaling the art.
In Illustrator, depending on the actual art, you may be able to use the Transform tab to resize the art - Window/Transform.